Expansible core for vulcanizing tires.



J. P. SMITH.

EXPANSiBLE CORE FOR VULCANIZING TiRES.

APPLICATION FILED AUG.8.19II.

Patented Apr. 1, 1919-.

PEJUL SEKJUL'H, OFAEON, H

I0, ASSIGNOR TO THE FIRESTONE TIRE EUBBER' :COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

EXPANSIBLE CORE FOR VULCAINIZDTG TEES.

1L2$45- d I v I Application filed dugust 8,

sure tohold the tire in while being cured.- It is necessary to ben these bags in order to get them into the uncured tire casing and .this bending or breaking will, after a few cures, form a ermanent depression or break in the surace of the core. The depression orbreak in the surface of the core will cause a correspond-I ing area of the tire casing to be without adequate pressure during curing, resulting in a soft spot in the tire. I It is the purpose of my invention to provide an air bag tionally. molded depression in order to cause the operator always to break or bend the bag at that'one place, and thus localizing any tendency for a depression in the surface o the bag. Having accomplished this purpose, I propose to provide a shield or bridge member permanently secured to the flap at a point near the artificially formed depres-' sion which shall extend over the depression and transmit the pressure of the bag evenly over all the area surrounding the depression. In the drawings: Figure 1 is anelevation and section of a tire casing showing the bag in the act of being placed in the casing. Fig. 2 is a cross section at the depression.

Fig. 3 is a side the depression. 7

In the drawings, 10 represents a tire casing in which the expansible bag 11 is being positioned. The bag may be made ofany suitable material, usually r bber and fabric. The outer or tread surface must be crimped or bent at one place in order to enable the bag to be placed in the tire. It would be possible to require the workman always to break the be at one point but it would be extremely di instructions were carried through the bag elevation of the bag at" out. I therefore an propose to form in the tread or periphery of Specification of Letters latent.

pression for when such he can always break the bag "breaks or crimps more easily at this point v his natural inclination is the following ings may tread portion,

'the shi in which there is an 'intenf smaller than the one underneath 1 smooth. The flap or 'cular or elliptical, of

of the tire and there is no Patented Apr. 1,1919. 1917. "Serial no; 1s5,1s5.

the bag, an artifically formed break or de-' the workman not only has a mark by which but as the bag to bend it there.

The artificial, or previously formed depresslon or break is made in the tread port1on of the bag while it isbeing cured and may easily be formed by inserting a piece of stock or some suitable is cured. In the be formed by a short piece of bead madepression is formed filler on the outside v of the bag and in the mold in which the bag form shown in the draw-' the depression is designated at 12 and I terial located transversely of the bag at its which bead material is removed after the bag is cured, forming a transverse groove in the bag.

Near the depression thereis attached tothe outer surface of the bag one end of a bridge piece or shield 13, the other end of e d lying on thebag at the opposite side of the "depression. This shield 1s preferably made of a plurality of layers of rubberized fabric, usually tapered ofi toward the edges by making each ply slightly it. A wide cover ply may be positioned over the top of the shield to make the surface of the shield bridge piece 13 is cira size suflicient to cover the depression andconsiderable of the bag about the depression, and stiff enough to transmit the pressure of the bag equally throughout its area so that the depression or break in the bag does'not afiect the tire casing but the region adjacent the break receives as much pressure as the remainder loss through unequal pressure spots. It isobvious that tions may be made without departing from the sprit of the invention or sacrificing any of its benefits.

I claim:

asv

changes and modifica- 1. An expansible core for curing tires tread portion of the bag, and a shield to cover said depression.

3. An expansible core for curing tires under pressure comprising an annular inflatable bag, a transverse depression in the tread portion of the bag, and a shield secured to said bag and extending over a short are on the tread portion of the bag to cover said depression:

4. An expansible core for curing tires under pressure, comprising an annular inflatable bag of rubber and-fabric, a transverse depression in the tread portion of the bag formed during the vulcanization thereof, and a shield secured to said bag and extending over a short are in the tread portion of thebag to cover the depression.

JOHN PAUL SMITH. 

